Apparatus and process for cutting extruded material

ABSTRACT

A rotating cutting apparatus comprising a cutting blade holder with at least one hole on the outside diameter of the cutting blade holder into which cutting blades are inserted and bonded to the cutting blade holder. The cutting blade holder encloses a center hole, so that the rotating cutting apparatus can be mounted to a drive shaft of machinery or secured to a cup that can be mounted to the drive shaft of machinery and driven by the machinery. The cutting blade holder can be made of a less expensive material, with only the cutting blade being made of higher-grade materials that maintains its cutting edge well. Additionally, in some arrangements of the present invention, the cutting blade may be sharpened on two sides so that the rotating cutting apparatus can be used for longer periods of time.

This Application is a Divisional Application claiming priority toapplication Ser. No. 09/777,735, filed on Feb. 6, 2001.

TECHNICAL FIELD

The present invention relates generally to the cutting of materialsproduced in a manufacturing process, and more particularly to materialsproduced in extrusion manufacturing processes.

BACKGROUND OF THE INVENTION

The invention relates generally to the cutting of materials during amanufacturing process, and more particularly, cutting materialsdelivered from an extrusion process.

It is known in manufacturing to produce a material in a continuouslyextruded stream, and cut the material to a desired size(s) as it leavesthe extruder. In extrusion manufacturing processes, cutting blades maybe used to cut materials being extruded, with the cutting blades oftenbeing mounted to the hub, or end, of extrusion machinery.

Conventionally, a cutting blade is made of a single piece of high-grademetal, often hardened, which has cutting edges formed integrally withthe body portion, the cutting edges being sharpened by using grinding,machining, or similar techniques. The prior art discloses cutting bladesmade of a single cast, died or cut material that is then sharpened alongthe edge. One practical drawback of this conventional technology is thatwhen the cutting edge(s) becomes dull, the production process must beshut down so that the cutting blade may be removed, sharpened andre-installed, or replaced with a new blade. Further, dull blades canlead to misshapen products. The cost of blades, along with the cost oflost production time when the process had to be stopped for the bladesto be replaced can be high, in part because the entire cutting mechanismis made from a single, relatively expensive, material.

The foregoing problems have been mitigated in some cases where theblades are sharpened on both sides, which reduces the frequency ofsharpening, but the blades are still expensive. With such aconfiguration, when the initial edges become dull, the entire cuttinghead is removed, reversed, and reattached so that a new set of sharpedges are available for use. To compensate for such expense, separatecutting blades, which may be sharpened or replaced individually, may beattached to a cutting blade holder, which is secured to the hub or endof the extrusion machinery. Generally, cutting blades are attached tothe cutting blade holder using screws. Difficulty occurs when the screwsused to attach the blades loosen during use. This requires the processto be shut down so that the screws can be tightened or replaced. Also,the tolerance between the blade and extruder equipment is very tight,frequently less than a few thousandths of an inch, to ensure precisemetering of product. Harder materials, such as various forms of carbide,are not suitable for use as a single, integral piece because the carbideis too brittle to be worked in this configuration, and such large piecesof carbide would be very expensive.

What is needed, therefore, is a method and apparatus for cuttingextruded materials that enables cutting blades to have longer cuttinglife, and that are relatively easy and inexpensive to replace when thecutting edge is no longer sharp.

SUMMARY OF THE INVENTION

The present invention, accordingly, provides for bonding individualcutting blades to a securing mechanism to produce a less expensivecutting mechanism that is light-weight enough to not distort the productbeing cut. To this end, a cutting blade holder with at least twochannels in the edge is used, and a cutting blade is inserted in eachchannel on the cutting blade holder, and bonded to the cutting bladeholder. Alternatively, each cutting blade may be bonded to a separatecutting blade holder, with at least two such assemblies secured to arotatable cup attachable to a rotating mechanism such as an extrudershaft.

In one arrangement, the cutting blade holder circumscribes a slot thatcan be attached to a commercially available cup or cutter head that fitsover the end or hub of the extrusion machinery.

An advantage achieved with the present invention is that only thecutting blades need to be made of a high-quality, wear-resistant metal,such as tungsten carbide or carbide coated metals. The cutting bladeholder may be made of a material such as a mild steel, which may bebonded to the cutting blades, thus reducing overall material costssubstantially.

Another advantage achieved with the present invention is that thecutting blades may be readily secured into the cutting blade holder bymeans such as brazing or use of a bonding material, which bonds thecutting blade holder and cutting blade materials together when heated.This reduces the time necessary to secure blades to the cutting bladeholder by eliminating the need to drill holes in the cutting blades andcutting blade holder and then using screws or other fastening hardwareto hold the pieces together. Depending on the bonding material used,this process may be reversed and repeated when replacement blades needto be secured to the cutting blade holder.

A further advantage achieved with the present invention is that theweight of the assembled cutting blade assembly is less than those inwhich cutting blades are secured to the cutting blade holder with screwsor other mechanical devices, resulting in fewer problems of deformationof the cut product being produced due to the weight of the cutting bladeassembly. This is especially important with products that are verylightweight, fine or small in size, and therefore more likely to bedeformed.

Still another advantage achieved with the present invention is that incertain arrangements, the cutting blade may be sharpened on both sidesso that when the cutting edge on one side of the blades becomes dull,the cutting blade holder may be reversed on the mounting hub. Thislengthens the amount of time a cutting mechanism may be used before itmust be removed and sharpened, resulting in less down time on productionlines.

As a result of the foregoing, another advantage achieved with thepresent invention is that when old cutting blades may not be sharpenedagain and ultimately need to be replaced, the old cutting blades may bede-bonded, and the cutting blade holder may be reused with new cuttingblades secured thereto, further reducing costs.

Another advantage achieved with the present invention is that after thecutting blade is secured into the cutting blade holder, the cuttingblade may be sharpened as necessary to ensure the cutting edge is flatand perpendicular to the material being cut, thus ensuring the materialis not deformed when it is being cut.

Another advantage achieved with the present invention is that the numbercutting blades around the diameter of the extrusion drive machinery maybe increased because the width and weight of the cutting blade assemblyis reduced. More cutting blades results in more frequent cuts, and thusreduces the speed at which the cutting mechanism needs to rotate for agiven size of cut, which reduces the wear on the equipment. The rotatingspeed is typically between 1 and 1500 revolutions per minute (RPM), with600 RPM being an optimal rotating speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of an arrangement of the present invention.

FIG. 2 is a view showing the cutting blade and cutting blade holderaccording to the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Typically, as shown in FIG. 1, cutting blades 60 are inclined at anangle with respect to a plane defined by the end of the cup 80, and theblades extend past such plane by a selected distance. Accordingly, whenthe cutting blade assembly is placed on a planar surface, such as a flattable, it is supported on the cutting blades 60. For precise, repeatablecuts, the edge 60 a of each blade 60 as shown in FIG. 2 must be arepeatable distance from the face of the extruder die when attached foruse. To achieve this result, each blade 60 and its edge 60 a, uponassembly, is measured for deviation from a common plane. Typically, themaximum deviation from a common plane between blades is less than 0.005inches, preferably less than 0.002 inches, and more preferably less than0.001 inches. Thus, in use, the initial cutting edges of the bladesrotate in a planar space not wider than 0.005 inches, preferably notwider than 0.002 inches, and most preferably not wider than 0.001inches.

Referring now to FIG. 1, the reference numeral 50 designates, ingeneral, a cutting blade assembly embodying features of the presentinvention. As viewed in FIG. 1, the cutting blade assembly 50 includes acutting blade holder 52, with a channel 54 along one end into which acutting blade 60 is inserted and secured by means of a bonding material30, so that cutting blade 60 extends transversely or at a right angle tocutting blade holder 52. The cutting blade holder 52 is preferably madeof a material such as a mild steel or other material that isinexpensive. The cutting blade holder 52 defines a center opening 52 aused to secure the cutting blade assembly 50 to a longitudinalreceptacle formed in the circumference of a commercially available,generally cylindrical cup 80, which is not separately claimed as part ofthe present invention, by means of a fastening mechanism 82, such as abolt, machine screw, or the like. The number of cutting blade assemblies50 attached to (and longitudinal receptacles formed in and about thecircumference of) the cup 80 may be varied to adapt the cutting bladeassembly 50 to the material being cut, and the frequency of cuts to bemade in the material. The cup 80 is mounted to the hub end of the shaft40 of an extrusion device (shown in phantom line). Cup 80 therefore hasa longitudinal and rotational axis. The cutting blade 60 is preferablymade of a material such as carbide, tungsten carbide or the like thatcan be sharpened and will retain a sharp edge. The cutting blade 60 isaligned in the channel 54 in the cutting blade holder 52, and secured bymeans of a bonding material 30, such as solder and the like, thatpreferably chemically bonds to the materials of the cutting blade holder52 and cutting blade 60. In some cases, the bonding material 30 usedmust be heated to stimulate the chemical reaction, and the bond becomespermanent when the bonding material 30 is returned to normal roomtemperature.

Referring now to FIG. 2, it can be seen that the cutting blade assembly50 comprises a cutting blade holder 52, a cutting blade 60, and bondingmaterial 30. The cutting blade holder 52 is preferably made of amaterial such as a mild steel or other material that is inexpensive. Thecutting blade holder 52 defines a center opening 52 a used to secure thecutting blade assembly 50. A channel 54 is contained in end of thecutting blade holder 52. The cutting blade 60 has a sharpened edge 60 acut at an angle to the channel 54 that is appropriate for the extrusionmechanism and material being extruded. As shown, each cutting blade 60and edge 60 a extends in a plane generally transverse or perpendicularto the rotational or longitudinal axis of cup 80 (and transverselyrelative to cutting blade holder 52) to position the cutting edges 60 ain a plane adapted to engage the material being extruded. The cuttingblade 60 is preferably made of tungsten-carbide, carbide, or other likehardened materials, or made of a less hard material and coated withcarbide, tungsten-carbide or other like hardened materials to provide asharp, long-lasting cutting edge.

It is understood that the present invention can take many forms andembodiments. The embodiments described herein are intended to illustraterather than to limit the invention. Accordingly, several variations maybe made in the foregoing without departing from the spirit or the scopeof the invention. For example, the cutting blade assembly 10, 50 may beattached to a shaft of a machine other than an extrusion machine, or maybe secured in a different manner than attaching to a machine shaft. Thecutting blade holder 12,52 and cutting blades 20, 60 may be made of avariety of materials, metallic or non-metallic, as appropriate to thecutting function being performed. The bonding material 30 may be solder,or some other glue, bonding material or the like that bonds well withthe materials of which the cutting blade holder 12, 52 and the cuttingblade 20, 60 are made.

Although illustrative embodiments of the invention have been shown anddescribed, a wide range of modification, change, and substitution iscontemplated in the foregoing disclosure and in some instances, somefeatures of the present invention may be employed without acorresponding use of the other features. Accordingly, it is appropriatethat the appended claims be construed broadly and in a manner consistentwith the scope of the invention.

1. An apparatus for cutting extruded materials comprising: a generallycylindrical cup adapted to be secured for rotation on a rotating shaft,the cup having an exterior, a rotational axis, and an end; a pluralityof longitudinal receptacles formed in the exterior of the cup parallelto the rotational axis and intersecting the end, wherein saidreceptacles each comprising two substantially parallel sides edgesconnected by an arcuate end edge; a plurality of cutting blade holders,each cutting blade holder having a longitudinal opening extending atleast a portion of the length of the cutting blade holder, the cuttingblade holder adapted to be received and removably secured in one of thelongitudinal receptacles by securing means extending radially from thecylindrical cup; a cutting blade including a cutting edge, the cuttingblade and cutting edge carried by and extending generally transverselyfrom each cutting blade holder and the rotational axis, the cutting edgeextending a selected distance past the rotational axis of the cup,wherein the cutting blade and holder together are being substantially“L” shaped.
 2. The apparatus of claim 1 wherein each cutting bladeholder is machined from a material that is responsive to an inductiveheating process.
 3. The apparatus of claim 1 wherein each cutting bladeholder is machined from a material that has a co-efficient of thermalexpansion less than 0.000007 inch/degree Fahrenheit.
 4. The apparatus ofclaim 1 wherein each cutting blade holder is molded.
 5. The apparatus ofclaim 1 wherein the cutting blade is bonded to the cutting blade holderby brazing with a solder material.
 6. The apparatus of claim 1 whereineach cutting blade is formed of a material other than carbide and coatedwith a layer of carbide.
 7. An apparatus for cutting extruded materialscomprising: a generally cylindrical cup adapted to be secured forrotation on a rotating shaft, the cup having an exterior, a rotationalaxis, and an end; a plurality of longitudinal receptacles formed in theexterior of the cup parallel to the rotational axis and intersecting theend, the longitudinal receptacles being spaced about the circumferenceof the cup, wherein said receptacles each comprising two substantiallyparallel sides edges connected by an arcuate end edge; a cutting bladeholder adapted to be received and removably secured in each longitudinalreceptacle by securing means extending radially from the cylindricalcup, the cutting blade holder having a longitudinal opening extending atleast a portion of the length of the cutting blade holder, the cuttingblade holder holding a cutting blade having a cutting edge, the cuttingblade and cutting edge extending generally transverse to the cuttingblade holder and rotational axis, the cutting edge extending a selecteddistance past the rotational axis of the cup, wherein the cutting bladeand holder together are substantially “L” shaped.
 8. The apparatus ofclaim 7 wherein each cutting blade holder is machined from a materialthat is responsive to an inductive heating process.
 9. The apparatus ofclaim 7 wherein each cutting blade holder is machined from a materialthat has a co-efficient of thermal expansion less than 0.000007inch/degree Fahrenheit.
 10. The apparatus of claim 7 wherein eachcutting blade holder is molded.
 11. The apparatus of claim 7 wherein thecutting blade is bonded to the cutting blade holder by brazing with asolder material.
 12. The apparatus of claim 7 wherein each cutting bladeis formed of a material other than carbide and coated with a layer ofcarbide.
 13. The apparatus of claim 7 wherein each cutting blade holderis secured in the longitudinal receptacle by a nut inserted through alongitudinal opening formed in the cutting blade holder and into areceptacle in the cup.
 14. The apparatus of claim 13 wherein the nut canbe loosened to reposition the cutting blade holder and attached cuttingblade to adjust the distance the cutting edge extends beyond therotational axis of the cup.